Manufacture of styrene and ethylbenzene



Patented Sept. 18, 1945 UNITED STATES @PATENT OFFICE" V \ass'issi QMANUFACTURE OF STYBENE AND ETHYLBENZENE Charles Weizmann, London,England No Drawing. Application June 11, 1043, Serial No. 490,518. InFrance January 17, 1940 temperature within the range of sorts 725 0.,

at substantially atmospheric pressures and ate. space velocity rangingfrom about 0.01 to 0.1 liter of oleilns, calculated on the liquid basis,per liter of catalyst per hour, and recovering from the reactionproducts a principal fraction having a boiling point range of about120-150" C. consisting substantially of styrene and ethylbenzene: thecatalyst used in said process being preferably selected from a groupconsisting of iron, copper, nickel. cobalt, molybdenum, manganese,tungsten, vanadium, silver and the platinum metals: all as more fullyhereinafter set forth and as claimed.

This application is a continuation-in-part {bf my copending application,Serial illed October 29, 1940. Q

It has been known for years that it is possible to convert olefins atleast partly into aromatic hydrocarbons byheating them in the presenceof metal catalysts under suitable conditions. The

Number 363.3%,

various processes described in the prior art have. i

usually been conducted in such fashion that the principal product hasbeen benzene. In the British patent to Greenstreet, No. 412,933. forexample, mixtures of olefinic and paraiiinic hydrocarbons are heatedwithin the temperature range of 600-1200 C. (preferably '700-850" C.) incontact with various solid materials including metals, and atatmospheric or higher pressures. The products produced are said to belargely aromatic in nature and to consist principally of benzene.

It has apparently not :beerr recognized by prior art investigators that.if the conditions of the process, including temperature and spacevelocity are carefully selected, it is possible to produce a productwhich is substantially completely aromatic, the largest part of whichconsists of a fraction, boiling between about 120 to 150 which consistssubstantially of ethylbenzene and styrene. when operated in this fashionthe secondary breakdown to benzene does not occuras it does in the priorart processes."

Ethylbenzene and styrene are, of course. the most valuable or thearomatics obtainable in any large quantities from such processes.Styrene forms the basis for a number of important thetic resins. and forBuns-S synthetic rubber;

8 Claims. 260-873) dition, it can be readily converted into styrene.

The present invention consists in a process for the manufacture ofaromatic hydrocarbons having eight carbon atoms in the course of whichlight oleflnes of low molecular weight, having from 2-5 carbon atomsare'passed over a finely divided metallic catalyst "of the hydrogenationand dehydrogenation type'at a temperature between about 600 to 725 C.and preferably at about atmospheric pressure.

The invention also consists in a process as set forth in the precedingparagraph according to which the metallic catalyst is a metal or alloyor mechanical mixture of metals or alloys capable of catalyzinghydrogenation or dehydrogenation reactions and is used preferably insuch a form as to present a large contact surface to the reactingmaterial.

The invention also consists in a process as set forth in the precedingparagraphs wherein the olefin, e. g. butylene, is passed through asteel. tube containing. the catalyst in the form of re- .ing reducedcopper wire gauze heated to 700 C.

The space velocity employed in this operation was 0.05 liter ofbutylene, calculated on the liquid basis, per liter of catalyst perhour. The eli'iuent from this-tube was cooled and condensed. -'l5 percent, of this liquid product distilled below 180 C. at atmosphericpressure. The residue crystallized spontaneously and consisted ofnaphthaiene and small quantities of other polycyclic aromatichydrocarbons. Upon careful fractionation of the light fraction, (boilingup to 180 C.) the following fractions were obtained:

. Percent Boiling below benzene 2 Benzene 30 Toluene 8 Ethylbenzene andstyrene 45 Styrene 15 The ratio of ethylbenzene to styrene obtained inmyprocess depends to some extent upon the while ethylbenzene ischaracterized by having I the very high octane number of 128 and, inadtemperature employed in the reaction zone. If

or of naphthalene, phenanthrene and anthracene are obtained. For exampleat lower temperatures the yield in low boiling aromatics is higher whileat higher temperatures the polycyclic hydrocarbons are formed in greaterquantities. At a temperature of about 700 C. the yield of styrene andethylbenzene reaches a maximum.

While I have described what I consider to be the best embodiments ofthis invention, it is evident, of course, that various modifications ofthe specific procedures described can be made without departing from thepurview of this invention. The metals found most satisfactory for use ascatalysts include copper, iron, nickel, cobalt, manganese, tungsten,vanadium, molybdenum, silver and the platinum metals. It is alsopossible to employ mixtures of these metals as catalysts, as w ll asalloys containing a plurality of these met s. In fact any metal capableof promoting hydrogenating and dehydrogenating reactions' can beemployed. Other modifications of my process which fall within the scopeof the following claims will be immediately evident to those skilled inthis art,

What I claim is: 1. In the manufacture of styrene and ethylbenzene, theprocess which comprises passing a low molecular olefin through aconversion zone, containing a finely divided metal hydrogenating:dehydrogenating catalyst, at substantially atmos-= pheric pressure, at atemperature within the range of about 600 to 725 C. and at a-spacevelocity ranging from about 0.01 to 0.1 liter of olefin,

calculated on the liquid basis, per liter of catalyst per hour, andfractionating the resulting products to obtain a principal fractionboiling between about 120 to 150 C. consisting substantially of styreneand ethylbenzene.

2. In the manufacture of styrene and ethylbenzene, the process whichcomprises passing an olefin containing from 2 to 5 carbon atoms basis,per liter of catalyst per hour and fractionatlng the resulting productsto obtain styrene and ethylbenzene in principal proportions.

l. In the manufacture of styrene and ethylbenzene, the process whichcomprises passing an olefin containing from 2 to 5 carbon atoms througha conversion zone containing a finely divided metalhydrogenating-dehydrogenating catalyst at substantially atmosphericpressure, at a temperature of about 700" C. and at a space velocityranging from about 0.01 to 0.1 liter of olefin, calculated on a liquidbasis, per liter of catalyst per hour, whereby styrene and ethyl benzeneare produced as a principal product, and fractionating the reactionproducts to recover said styrene and ethylbenzene.

5. The process of claim 2 wherein said olefin is butylene.

6. The process of claim 4 wherein said olefin is butylene.

7. In the manufacture of styrene and ethylbenzene, the process whichcomprises passing butylene through a conversion zone containing finelydivided copper at substantially atmospheric pressure, at a temperatureof about 700 C. and at a space velocity of about 0.05 liter of butylene,calculated on a liquid basis, per liter of catalyst per hour, wherebystyrene and ethylbenzene are formed as a principal product, andfracrtionating the reaction products to recover said styrene andethylbenzene.

8. In the production of aromatics by the cata-

